Objective: The purpose of this study is to test the association between joint hypermobility syndrome (JHS) and panic disorder (PD) and to determine whether mitral valve prolapse (MVP) modifies or accounts in part for the association. Method: A total of 115 subjects are included in this study in three groups. Group I (n = 42): panic disorder patients with MVP. Group II (n = 35): panic disorder patients without mitral valve prolapse. Group III (n = 38): control subjects who had mitral valve prolapse without any psychiatric illness. Beighton criteria were used to assess joint hypermobility syndrome. Two-dimensional and M-mode echocardiography was performed on each subject to detect mitral valve prolapse. Results: Joint hypermobility syndrome was found in 59.5% of panic disorder patients with mitral valve prolapse, in 42.9% of patients without mitral valve prolapse and in 52.6% of control subjects. Beighton scores was 4.93 +/- 2.97 in group I, 4.09 +/- 2.33 in group II, and 4.08 +/- 2.34 in group III. There was no significant difference between groups according to Beighton scores. Conclusion: We did not detect a statistically significant relationship between panic disorder and joint hypermobility syndrome. Mitral valve prolapse and joint hypermobility syndrome are known to be etiologically related and we suggest that mitral valve prolapse affects the prevalence of joint hypermobility syndrome in the panic disorder patients. (C) 2004 Published by Elsevier Inc.